Interlaminar lumbar interbody fusion system and associated robotic systems

ABSTRACT

Orthopedic implants, systems, instruments, and methods. A bi-portal lumbar interbody fusion system may include an expandable interbody implant and minimally invasive pedicle-based intradiscal fixation implants. The interbody and intradiscal implants may be installed with intelligent instrumentation capable of repeatably providing precision placement of the implants. The bi-portal system may be robotically-enabled to guide the instruments and implants along desired access trajectories to the surgical area.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 17/380,267 filed on Jul. 20, 2021, which isincorporated in its entirety herein.

FIELD OF THE INVENTION

The present application relates generally to orthopedic fixationdevices, such as lumbar interbody fusion implants, intradiscal implants,associated instruments, and associated methods, for example, for spinesurgery.

BACKGROUND OF THE INVENTION

Transforaminal lumbar interbody fusion (TLIF) procedures are a standardsurgery technique to provide support and stabilize the spinal vertebraand the disc space when treating a variety of spinal conditions, such asdegenerative disc disease and spinal stenosis with spondylolisthesis.Clinical treatment of spinal pathologies may include precise placementof an interbody to restore anterior column alignment with bilateralpedicle screw (BPS) fixation to stabilize two or more adjacent vertebralbodies adjacent to spinal fusion levels.

Various iatrogenic pathologies may occur in association with interbodyand bilateral pedicle screw placement. These pathologies may result fromthe surgical access window to the disc space, failure to precisely placethe interbody along the apophyseal ring for quality cortical bonesupport, and/or failure to restore normal anatomical spinal alignment.Iatrogenic pathologies associated with pedicle screw fixation, mayinclude, but are not limited to, misplacement of screws, muscle/ligamentdisruption during insertion, adjacent segment disease due to superioradjacent facet violation by the pedicle screw, and rod construct,procedural efficiency, and instrumentation failure.

The instrumentation needed to provide access into the disc through atubular approach, provide a valued decompression, complete a qualitydiscectomy efficiently, insert and deploy an interbody, and insert thepedicle screw and rod construct also require a multitude of radiographicimaging throughout the procedure. This all increases surgical operatingtime, radiation exposure, and can result in the misplacement of implantsand screws.

There exists a clinical need for a robotically enabled procedure thatprovides pre-operative planning that is compatible with navigated,intelligent instrumentation that (1) establishes safe and repeatabledirect decompression while gaining access to the disc space; (2)provides enhanced navigated, powered discectomy technique; (3) allowsfor precision placement of an expandable interbody that increasessurface area contact along the apophyseal ring through the posteriorapproach; and/or (4) utilizes a minimally invasive fixation method thatstabilizes the adjacent vertebral bodies without violating the superiorfacet.

SUMMARY OF THE INVENTION

To meet this and other needs, orthopedic implants, systems, instruments,and methods are provided. The implant system may include a three-leggedexpandable interbody used alone or in combination with one or morepedicle-based intradiscal fixation implants. The implants may beinstalled using a robotically-enabled bi-portal lumbar interbody fusionprocedure with intelligent instrumentation capable of repeatablyproviding clinically superior segmental correction through stabilizationand fixation methods that avoid violation of the superior adjacent facetjoint for patients with one- or two-level degenerative conditions. Theprocedure may include one or more aspects of the following workflowwhich may be assisted and enhanced using imaging, navigation and/orrobotics: (1) pre-operative planning; (2) end-effector set-up; (3)tubular access and decompression or alternative visualization portworkflows; (4) bi-portal implant cannula insertion; (5) bi-portaldiscectomy; (6) interbody deployment, positioning, and expansion; (7)nitinol fixation construction; and (8) final verification.

According to one embodiment, an orthopedic system for stabilizing thespine includes an expandable interbody implant and first and secondpedicle-based intradiscal implants. The expandable interbody implant mayinclude a first expandable lateral leg, a second expandable lateral leg,and a third central leg pivotably connected between the first and secondlateral legs. The first and second lateral legs are independentlyexpandable in height to provide lordotic and/or coronal adjustments. Thefirst and second pedicle-based intradiscal implants may each include anitinol rod and a pedicle screw securable to the nitinol rod.

The pedicle-based intradiscal implant may include one or more of thefollowing features. The nitinol rod may extend from a proximal endconfigured to mate with the pedicle screw to a distal end configured toengage bone. The nitinol rod may have a naturally curved state and thenitinol rod may be straightened for deployment. The curved state of thenitinol rod may be an arc up to 180°. The nitinol rod may have apolygonal cross-section with planar faces. The nitinol rod may beconfigured to be inserted through a pedicle of an inferior vertebra,through a vertebral body of the inferior vertebra, through a disc space,and into a vertebral body of a superior vertebra. The proximal end ofthe nitinol rod may include an externally threaded portion configured tomate with an internally threaded portion of the pedicle screw. Thepedicle screw may include a screw head with a threaded or roughenedtexture configured to be engaged by a polyaxial tulip head.

The expandable interbody implant may include one or more of thefollowing features. The first and second lateral legs of the expandableinterbody implant may be configured to angulate at one or more pins toincrease the overall footprint of the implant. The first and secondlateral legs may each include an actuation assembly including a drivescrew configured to expand the first and second lateral legs and thecentral leg of the expandable interbody implant.

According to one embodiment, a pedicle-based intradiscal implantincludes a bendable rod and a pedicle screw. The bendable rod may becomprised of a shape-memory material, such as nitinol. The bendable rodmay extend from a proximal end having an outer threaded portion to adistal end with a sharp tip configured to engage bone. The bendable rodmay have a polygonal cross-section with planar faces. The pedicle screwmay extend from a proximal end with a screw head to a distal end with atip configured to engage the bendable rod. The pedicle screw may have athreaded shaft with a hollow body for receiving the proximal end of thebendable rod. The threaded shaft may define an internal threaded portionconfigured to mate with the outer threaded portion of the bendable rod.

According to another embodiment, a system for deploying thepedicle-based intradiscal implant includes a deployment instrumentconfigured to load and deploy the bendable rod. The deploymentinstrument includes a body having a longitudinal axis with a straightdeployment tube configured to draw in the curved rod, therebystraightening the rod when held within the deployment tube, and a shaftwith an impaction cap. The deployment instrument may include a T-shapedhandle with a socket configured to be received over the shaft with theimpaction cap. When the handle is rotated about the longitudinal axis ofthe deployment instrument, the bendable rod is drawn into the deploymenttube. When the shaft of the deployment instrument is translated distallyalong the longitudinal axis of the instrument by striking the impactioncap, the shaft forces the bendable rod to deploy out of the deploymenttube.

According to another embodiment, a method for stabilizing the spineincludes (1) positioning an expandable interbody implant in a disc spacebetween superior and inferior vertebrae, the expandable interbodyimplant having three articulating and expandable legs; (2) deploying afirst bendable rod from an ipsilateral pedicle of the inferior vertebra,thru the disc space, and into a vertebral body of the superior vertebra;(3) inserting a first pedicle screw through the ipsilateral pedicle ofthe inferior vertebra and driving the first pedicle screw over the firstbendable rod to anchor the first bendable rod; (4) deploying a secondbendable rod from a contralateral pedicle of the inferior pedicle, thruthe disc space, and into the vertebral body of the superior vertebra;and (5) inserting a second pedicle screw through the contralateralpedicle of the inferior pedicle and driving the second pedicle screwover the second bendable rod to anchor the second bendable rod.

The method may further include articulating the three legs of theexpandable interbody implant relative to one another to increase theoverall footprint of the implant. The expandable interbody implant maybe placed along the apophyseal ring of the vertebrae for cortical bonesupport. The expandable interbody implant may be expanded toindependently control sagittal and coronal correction. The expandableinterbody implant may be positioned in the disc space by inserting amagnetic cable assembly attached to the expandable interbody implantthrough an ipsilateral cannula, inserting an articulating magnetretrieval tool through a contralateral cannula to magnetically attractand connect to the magnetic cable assembly, and retracting thearticulating magnet retrieval tool back through the contralateralcannula, thereby pulling the cable assembly into the contralateralcannula and positioning the expandable interbody implant in the discspace. The first intradiscal implant may be deployed through anipsilateral cannula and the second intradiscal implant may be deployedthrough a contralateral cannula. The first and second intradiscalimplants may be positioned medially relative to the expandable interbodyimplant. The first and second bendable rods may each be deployed with adeployment instrument having a deployment tube and a shaft with animpaction cap. Each bendable rod may be deployed by striking theimpaction cap, thereby forcing the rod to deploy out of the deploymenttube.

According to another embodiment, a method of installing an expandableinterbody implant in a disc space between two adjacent vertebrae mayinclude: (1) inserting a cable assembly through an ipsilateral cannula,the cable assembly including a cable with a magnetic tip at one end andattachable to an expandable interbody implant at the other end, theexpandable interbody implant having a first expandable lateral leg, asecond expandable lateral leg, and a third central leg pivotablyconnected between the first and second lateral legs; (2) inserting anarticulating magnet retrieval tool through a contralateral cannula; (3)articulating and guiding the articulating magnet retrieval tool towardthe ipsilateral cannula to magnetically attract and connect to themagnetic tip of the cable assembly; and (4) retracting the articulatingmagnet retrieval tool back through the contralateral cannula, therebypulling the cable assembly into the contralateral cannula andpositioning the expandable interbody implant in the disc space.

The method of installing the expandable interbody implant may furtherinclude threading the cable assembly on the first expandable lateral legof the expandable interbody implant before inserting the cable assemblythrough the ipsilateral cannula. The method may include attaching afirst inserter to the expandable interbody implant while placing thecable under tension. The method may include feeding the expandableinterbody implant through the ipsilateral cannula with the firstinserter while the cable assembly pulls the expandable interbody implantinto an articulated U-shaped position. After removing the cable assemblyfrom the expandable interbody implant, a second inserter may be attachedto the expandable interbody implant such that the first and secondinserters are rigidly connected to the first and second lateral legs,respectively, thereby providing for dual control of the expandableinterbody implant. The method may also include inserting a driverthrough each of the first and second inserters to independently expandthe first and second lateral legs to control sagittal and coronalcorrection.

According to yet another embodiment, a method for installing apedicle-based intradiscal implant may include (1) loading a deploymentinstrument including a body having a longitudinal axis with a straightdeployment tube and a shaft with an impaction cap, by drawing a rodhaving a naturally curved shape into the straight deployment tube,thereby straightening the rod when held within the deployment tube; (2)positioning the deployment tube at a pedicle of an inferior vertebra;and (3) deploying the rod from the deployment instrument by striking theimpaction cap to translate the shaft of the deployment instrument alongthe longitudinal axis, thereby forcing the rod to deploy out of thedeployment tube, wherein once deployed, the rod extends from thepedicle, thru a disc space, and into a vertebral body of a superiorvertebra. The method for installing the pedicle-based intradiscalimplant may further include securing a pedicle screw through the pedicleof the inferior vertebra and driving the pedicle screw over one end ofthe rod to anchor the rod.

According to another embodiment, a bi-portal robotically-enabled systemmay include a robotic system and a bi-portal assembly. The roboticsystem may include a base, including a computer, a displayelectronically coupled to the computer, a robot arm electronicallycoupled to the computer and movable based on commands processed by thecomputer, an end-effector having a guide tube electronically coupled tothe robot arm, the guide tube having a central longitudinal axis, and acamera configured to detect one or more tracking markers. The bi-portalassembly may include a guide bar assembly supporting first and secondnavigated cannula assemblies. The guide bar assembly may include acentral guide bar configured to be inserted into the guide tube andfirst and second lateral wings positioned on opposite sides of the guidebar. The first and second navigated cannula assemblies may each includea hollow tubular cannula configured to guide an instrument placedthrough the respective cannula along a desired access trajectory to asurgical area.

The bi-portal robotically-enabled system may include one or more of thefollowing features. The bi-portal assembly may be configured to pivotabout the central longitudinal axis of the guide tube of theend-effector. The first and second navigated cannula assemblies may eachbe configured to independently angulate with respect to the centrallongitudinal axis of the guide tube, thereby providing the desiredaccess trajectories to the surgical area. The width between the cannulasof the first and second navigated cannula assemblies may be adjustable.The bi-portal assembly may include a plurality of tracking markersconfigured to monitor the guide bar assembly and first and secondnavigated cannula assemblies, thereby providing navigated and/or roboticassistance. The first lateral wing may support the first navigatedcannula via a first supporting arm and the second lateral wing maysupport the second navigated cannula via a second supporting arm. Thefirst and second lateral wings may each include an elongate slot, andthe navigated cannula assemblies may slide along the respective slots toadjust the width and/or angulation of the cannulas. The guide bar may beconfigured to slide into and lock axially to the guide tube of theend-effector with an axial locking cap. The axial locking cap mayinclude a locking button configured to engage with a groove on the guidebar. Rotational movement of the guide bar assembly may be lockable witha central wheel handle lock.

According to another embodiment, a bi-portal assembly may include aguide bar assembly and first and second navigated cannula assemblies.The guide bar assembly may include a central guide bar configured to beinserted into a guide tube of a robot system and first and secondlateral wings positioned on opposite sides of the guide bar. The firstand second lateral wings may each including an elongate slot. The firstnavigated cannula assembly may include a first cannula coupled to thefirst lateral wing. The first cannula may be configured to guide aninstrument placed through the first cannula along a first accesstrajectory. The second navigated cannula assembly may include a secondcannula coupled to the second lateral wing. The second cannula may beconfigured to guide an instrument placed through the second cannulaalong a second access trajectory. The first and second navigated cannulaassemblies may slide along the respective slots in the first and secondlateral wings to adjust the width and/or angulation of the first andsecond cannulas.

The bi-portal assembly may include one or more of the followingfeatures. The first and second navigated cannula assemblies may movealong one or more ratchets, thereby providing for incremental adjustmentof the width and/or angle of the first and second cannulas. The ratchetsmay include curvilinear ratchets configured to mimic the shape of thefirst and second lateral wings. The ratchets may be positioned above andbelow each of the elongate slots. The first and second navigated cannulaassemblies may each include a rotatable knob configured to independentlylock a final position of the first and second cannulas. The bi-portalassembly may include a plurality of tracking markers on the guide bar,the first and second lateral wings, and the first and second cannulas.

According to yet another embodiment, a bi-portal robotically-enabledmethod may include: (1) performing pre-operative planning with a roboticsystem having an end-effector with a guide tube including takingpre-operative images and planning positioning of one or more implants;(2) introducing a guide bar of a bi-portal assembly into the guide tubeof the end-effector, the bi-portal assembly comprising a guide barassembly supporting first and second navigated cannula assemblies eachconfigured to guide an instrument along a desired access trajectory; (3)accessing a surgical site through the first and second navigated cannulaassemblies to perform a decompression; (4) positioning implant cannulasthrough the first and second navigated cannula assemblies; (5)performing a discectomy through the implant cannulas; (6) deploying aninterbody implant through the implant cannulas; (7) installingintradiscal implants through the guide tube of the end-effector; and (8)verifying final positioning of the interbody and intradiscal implants.The first and second navigated cannula assemblies may each include anadjustable depth stop configured to set the access depth into thesurgical site.

Also provided are kits including implants of varying types and sizes,rods, fasteners or anchors, various instruments and tools, k-wires, andother components for performing the procedures.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein:

FIGS. 1A-1C shows anterior, lateral, and axial views, respectively, ofadjacent vertebrae with a fixation system including a three-leggedexpandable interbody and a pair of pedicle-based intradiscal fixationimplants according to one embodiment;

FIGS. 2A-2D show top, rear, and side views, respectively, of athree-legged expandable interbody implant according to one embodiment;

FIG. 3 shows a perspective view of a pedicle-based intradiscal fixationimplant according to one embodiment;

FIGS. 4A-4B shows the components of the pedicle-based intradiscalfixation implant of FIG. 3 including the nitinol rod and a pedicle screwcoupled to the nitinol rod, respectively;

FIG. 5 is a flowchart of a workflow for a bi-portal lumbar interbodyfusion procedure according to one embodiment;

FIGS. 6A-6B depict a robotic surgical system including an end-effectorwith a guide tube according to one embodiment;

FIG. 7 shows a perspective view of a robotically-enabled bi-portalposterior access assembly received in the guide tube of the end-effectorof FIG. 6B according to one embodiment;

FIGS. 8A-8C show a method of attaching the guide bar assembly of thebi-portal assembly to the guide tube of the end-effector, rotating thebi-portal assembly, and aligning the bi-portal assembly for access tothe spine according to one embodiment;

FIGS. 9A-9B depict rear views of the bi-portal assembly showingadjustment of the width and angles of the cannulas for installation ofthe expandable interbody implant according to one embodiment;

FIG. 10 shows a front view of the bi-portal assembly with adjustablestops for controlling the access depth of an instrument through thecannulas according to one embodiment;

FIGS. 11A-11B show front and side views, respectively, of the bi-portalassembly with navigated instruments positioned through the cannulas toaccess the disc space according to one embodiment;

FIGS. 12A-12B show front and side views, respectively, of the bi-portalassembly with alternative instruments positioned through the cannulas toaccess the disc space according to one embodiment;

FIGS. 13A-13C show port assemblies connected to the guide bar assemblywhere width and angulation between the ports, conical angulation of theports, and the depth of the ports may be adjusted to increasevisualization to the surgical site according to one embodiment;

FIGS. 14A-14D show exploded and assembled views of a navigatedinstrument assembly with an adjustable stop for controlling the accessdepth according to one embodiment;

FIGS. 15A-15C show an adjustable implant cannula and a cannula dilatorloaded in the implant cannula according to one embodiment;

FIGS. 16A-16B show the bi-portal assembly with the adjustable implantcannulas and the cannula dilators, respectively, according to oneembodiment;

FIGS. 17A-17B show a navigated discectomy instrument according to oneembodiment;

FIGS. 18A-18C show a navigated discectomy procedure through thebi-portal assembly with the adjustable implant cannulas according to oneembodiment;

FIGS. 19A-19B show a discectomy procedure with a powered discectomyinstrument according to another embodiment;

FIGS. 20A-20C show perspective, side, and front views, respectively, ofa tissue cutter for the powered discectomy instrument according to oneembodiment;

FIGS. 21A-21F show a method of installing the articulating expandableimplant of FIGS. 2A-2D in a disc space with a magnetic retrieval anddeployment tool and a fishing cable assembly according to oneembodiment;

FIG. 22 shows a complete overview of the bi-portal assembly withnavigable inserters positioned through the ipsilateral and contralateralimplant cannulas according to one embodiment;

FIGS. 23A-23B show front and perspective views, respectively, of thebi-portal assembly with ipsilateral and contralateral inserters snap fitto the respective inserters according to one embodiment;

FIGS. 24A-24C show a nitinol rod fixation instrument configured forloading and deploying the nitinol rod of the pedicle-based intradiscalfixation implant shown in FIGS. 3 and 4A-4B;

FIGS. 25A-25F show a system and method for deploying the nitinolfixation rod and attaching the pedicle screw to the rod according to oneembodiment; and

FIGS. 26A-26D show posterior, lateral, anterior, and intradiscal views,respectively, of the final construct including the expandable interbodyimplant and two intradiscal fixation devices according to oneembodiment.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the disclosure are generally directed to orthopedicimplants, systems, instruments, and methods. In particular, a bi-portallumbar interbody fusion procedure may include an expandable interbodythat increases surface area contact along the apophyseal ring throughthe posterior approach and minimally invasive pedicle-based intradiscalfixation implants that stabilize the adjacent vertebral bodies withoutviolating the superior facet. The interbody and intradiscal implants maybe installed with intelligent instrumentation capable of repeatablyproviding precision placement of the implants. The procedure may beperformed with or without navigation and/or robotic assistance. Therobotically-enabled procedure may utilize imaging, navigation, androbotics to enhance the quality and efficiency of the posteriorprocedure through planning and navigable instrumentation.

Additional aspects, advantages and/or other features of exampleembodiments of the invention will become apparent in view of thefollowing detailed description. It should be apparent to those skilledin the art that the described embodiments provided herein are merelyexemplary and illustrative and not limiting. Numerous embodiments andmodifications thereof are contemplated as falling within the scope ofthis disclosure and equivalents thereto.

Referring now to FIGS. 1A-1C, an interlaminar lumbar interbody fusionsystem or orthopedic fixation system 10 is shown for fusing two adjacentvertebrae 2. The fixation system 10 may include an expandable interbodyimplant 12 and one or more pedicle-based fixation implants 14. Theexpandable interbody implant 12 is positioned in the disc space 4between the superior and inferior vertebral bodies 6. The interbodyimplant 12 may be placed along the apophyseal ring for cortical bonesupport. The expandable interbody implant 12 may include dual,independent expansion and angulation to adjust lordosis and/or coronalbalance, thereby allowing for restoration of spinal anatomicalalignment. The pedicle fixation implant 14 may include an intradiscaldevice configured to be deployed from the inferior pedicle 8, thruinferior vertebral body 6, thru the intradiscal space 4, and into thesuperior vertebral body 6. First and second pedicle fixation implants 14may be positioned through the pedicles 8 of the inferior vertebra 2 andmedially relative to the interbody implant 12. The fixation system 10may provide for superior segmental correction from stabilization device12 with independently controlled sagittal and coronal correction andincreased stability from increased endplate contact along the apophysealring as well as a fixation construct that avoids violation of thesuperior facet joint and the potential iatrogenic effects of atraditional bilateral pedicle construct.

Turning now to FIGS. 2A-2D, the expandable interbody implant 12 mayinclude three sections or legs 20, 22, 24, which are configured toarticulate or pivot relative to one another at pins 26 to increase theoverall width or footprint of the implant 12. The implant 12 may includea first expandable lateral leg 20, a second expandable lateral leg 22,and a third anterior leg or central leg 24 with link plates 28, whichconnect the first and second lateral legs 20, 22. Each of the lateralleg 20, 22 may include an actuation assembly 30, for example, includinga drive screw or actuator configured to move a plurality of drivingramps, which expand the endplates of the lateral legs 20, 22 in height.When the first and/or second lateral legs 20, 22 are independentlyexpanded in height, the attached link plates 28 are configured topassively increase in height, thereby providing lordotic and/or coronaladjustments.

Turning now to FIGS. 3 and 4A-4B, the pedicle-based fixation implant 14may be made up of two biocompatible components: a rod 40 and a screw 42.The rod 40 may be composed of nitinol or other shape-memory material,which allows the rod 40 to bend into a curved state upon deployment. Thenitinol rod 40 may include a proximal end 44 configured to mate with thepedicle screw 42 and a distal end 46 configured to engage bone. Thesuper elasticity of nitinol allows for the material to be drawn into astraight configuration from its naturally curved state. In its relaxedstate, the nitinol rod 40 may have a curve or arc of 180° or a curve orarc up to 180°. The body of the nitinol rod 40 may have a polygonalcross-section with planar faces. For example, the body may have aquadrilateral cross-sectional shape, such as a square. The distal end 46may include a pointed or sharp tip configured to pierce bone. Theproximal end 44 may include a threaded portion 48 which mates with thescrew 42. The nitinol rod 40 may be deployed through the pedicle 8 ofthe inferior vertebra 2 and the distal end 46 may pass through thevertebral body 6 of the inferior vertebra 2, through the disc space 4,and into the vertebral body 6 of the superior vertebra 2.

The screw 42 may include a pedicle screw that extends from a proximalend with a screw head 50 to a distal end with a tip 52 configured toengage the nitinol rod 40. The screw 42 may be comprised of titanium orany suitable biocompatible material. The screw head 52 may define adrive recess that can be engaged by a screw-driving instrument or otherdevice. The screw head 50 may have any general shape. In the embodimentshown, the screw head 50 has a curved or spherical surface that isthreaded or roughened. The screw head 50 may interface with a polyaxialtulip head, which may retain a spinal rod. Examples of tulip heads androd constructs are described in more detail, for example, in U.S. Pat.No. 10,368,917, which is incorporated by reference herein in itsentirety for all purposes. The screw 42 has a threaded shaft 54configured to engage bone. It will be appreciated that the threadedshaft 54 may have a number of different features, such as lead(s),thread pitch, thread angle, shaft diameter to thread diameter, overallshaft shape, and the like. It is also contemplated that the threadedshaft 54 could be substituted with another suitable bone fastener, suchas an anchor, clamp, or the like configured to engage bone.

The threaded shaft 54 of the pedicle screw 42 may define a hollow bodyfor receiving the proximal end 44 of the nitinol rod 40. The hollow bodymay extend along a portion or the entire length of the screw 42. Thehollow body defines an internal threaded portion configured to mate withthe outer threaded portion 48 of the nitinol rod 40. It will beappreciated that one or more additional features may be used to lock thescrew 42 to the nitinol rod 40, such as a snap ring within the pediclescrew 42 configured to snap into an external groove 56 of the nitinolrod 40. The pedicle screw 42 may be deployed through the same pedicle 8of the inferior vertebra 2 as the nitinol rod 40. The pedicle screw 42is inserted and driven over the proximal threads 48 of the nitinol rod40 to purchase the existing cortical bone in the pedicle 8 and anchorthe proximal end 44 of the nitinol rod 40 to the inferior pedicle 8.

Turning now to FIG. 5 , the interlaminar lumbar interbody fusionprocedure may have a structured workflow 60 for preparing and installingthe expandable interbody implant 12 and pedicle-based fixation implants14. The workflow 60 may include one or more of the following steps. (1)Pre-operative imaging 62 may be performed of the patient anatomy, suchas CT (computed tomography), MRI (magnetic resonance imaging), or otherrelevant imaging. (2) Pre-operative planning 64 may provide for plannedplacement of the expandable interbody 12, planned access paths, plannedplacement of the nitinol rod fixation devices 14, and a review of theplan strategy. (3) Access and decompression 66 of the disc space 4 maybe set according to the plan. The disc space 4 may be accessed through aMIS (minimally invasive surgery) or open surgery. The access may utilizenavigated instrumentation and/or robotic assistance. (5) A bi-portaldiscectomy 68 may be performed to increase the efficiency and overallquality of soft tissue removal. (6) Interbody deployment 70 may includedeploying, positioning, articulating, and expanding the implant 12. (7)Nitinol fixation deployment 72 may include deploying the pedicle-basedintradiscal fixation implants 14 through the pedicles 8 of the inferiorvertebra 2 and into the vertebral body 6 of the superior vertebra 2. (8)Final verification 74 may include checking the location of the interbodyand pedicle-based fixation implants 12, 14 and ensuring the finalconstruct is accomplishing the pre-operative plan and achieving thedesired correction. The workflow 60 may be assisted and enhanced usingimaging, navigation and/or robotics.

FIGS. 6A-6B illustrate an example of a surgical robotic and navigationsystem 80. The surgical robot system 80 may include, for example, asurgical robot 82, a base 86 including a computer, a display or monitor88 (and optional wireless tablet) electronically coupled to thecomputer, one or more robot arms 84 controlled by the computer, and anend-effector 90 including a guide tube 92 electronically coupled to therobot arm 84. The surgical robot system 80 may also utilize a camera 94,for example, positioned on a separate camera stand 96. The camera stand96 can have any suitable configuration to move, orient, and support thecamera 94 in a desired position. The camera 94 may include any suitablecamera or cameras, such as one or more infrared cameras (e.g., bifocalor stereophotogrammetric cameras), able to identify, for example, activeand/or passive tracking markers in a given measurement volume viewablefrom the perspective of the camera 94. The camera 94 may scan the givenmeasurement volume and detect the light that comes from the markers inorder to identify and determine the position of the markers inthree-dimensions. For example, active markers may includeinfrared-emitting markers that are activated by an electrical signal(e.g., infrared light emitting diodes (LEDs)), and passive markers mayinclude retro-reflective markers that reflect infrared light (e.g., theyreflect incoming IR radiation into the direction of the incoming light),for example, emitted by illuminators on the camera 94 or anothersuitable device.

The surgical robot 82 is able to control the translation and orientationof the end-effector 90. The robot 82 may be able to move end-effector 90along x-, y-, and z-axes, for example. The end-effector 90 can beconfigured for selective rotation about one or more of the x-, y-, andz-axis, and a Z Frame axis (such that one or more of the Euler Angles(e.g., roll, pitch, and/or yaw) associated with end-effector 90 can beselectively controlled). In some exemplary embodiments, selectivecontrol of the translation and orientation of end-effector 90 can permitperformance of medical procedures with significantly improved accuracy.

The robotic positioning system 82 includes one or more computercontrolled robotic arms 84 to assist the surgeon in planning theposition of one or more navigated instruments relative to intraoperativepatient images. The system 80 includes 2D & 3D imaging software thatallows for preoperative planning, navigation, and guidance through adynamic reference base, navigated instruments, and positioning camera 94for the placement of spine, orthopedic, or other devices. Furtherexamples of surgical robotic and/or navigation systems can be found, forexample, in U.S. Pat. Nos. 10,675,094 and 9,782,229, which areincorporated by reference herein in their entireties for all purposes.

Turning now to FIGS. 7 and 8A-8C, a bi-portal posterior access systemand technique is shown, which may be robotically-enabled to assist asurgeon during surgery. A bi-portal assembly 100 may be configured toattach to the guide tube 92 of the end-effector 90 of the robot 82. Inthis manner, the robot 82 is configured to control the location andorientation of the bi-portal assembly 100 relative to the surgical area.The bi-portal assembly 100 includes a guide bar assembly 102, a firstnavigated cannula assembly 104, and a second navigated cannula assembly106. The entire bi-portal assembly 100 is configured to pivot or rotateabout the central longitudinal axis A of the guide tube 92 of theend-effector 90. The first and second navigated cannula assemblies 104,106 are each configured to independently angulate with respect to thecentral longitudinal axis A, thereby providing the desired accesstrajectories to the surgical area. The bi-portal assembly 100 mayinclude a plurality of tracking markers 108 configured to monitor thevarious features of the bi-portal assembly 100 and provide navigatedand/or robotic assistance during the surgery.

As best seen in FIG. 8A, the guide bar assembly 102 includes a centralguide bar 110 configured to be inserted into the bottom of the guidetube 92 of the end-effector 90. The guide bar assembly 102 includes acentral support arm 112 for holding first and second lateral wings 114,116. The first and second lateral wings 114, 116 are positioned onopposite sides of the guide bar 110 and extend outwardly in oppositedirections from one another. The first lateral wing 114 supports a firstnavigated cannula 120 via a first supporting arm 124 and the secondlateral wing 116 supports a second navigated cannula 122 via a secondsupporting arm 126. The navigated cannulas 120, 122 each include a longhollow tubular body defining a central longitudinal axis A1, A2,respectively. Each navigated cannula 120, 122 is configured to guide aninstrument placed through the respective cannula 120, 122 along thedesired trajectory to the surgical site.

With further emphasis on FIG. 8A, the guide bar 110 is configured toslide into and lock axially to the guide tube 92 of the end-effector 90.For example, the guide bar 110 may snap into an axial locking cap 130.The axial locking cap 130 may be snapped on an inside portion of theend-effector 90 to avoid blocking the infrared LEDs 132, which act astracking markers for the end-effector 90. An upper portion of thelocking cap 130 may rest on a top surface of the end-effector 90 abovethe guide tube 92. The locking cap 130 may include a locking button 134configured to engage with a groove 136 of the guide bar 110. The groove136 may be located between two annular rings at the proximal end of theguide bar 110. The locking button 134 may be spring-loaded toautomatically engage the groove 136 when the guide bar 110 is slidupwards through the inner diameter of the guide tube 92 of theend-effector 90. When locked with the locking cap 130, the guide barassembly 102 is axially constrained to the guide tube 92, but is stillpermitted to rotate about the longitudinal axis A of the guide tube 92.Alternatively, the locking connection to the end-effector 90 of therobot 82 could be built into the guide bar 110 rather connecting throughthe end-effector 90. It will be appreciated that other suitable lockingmechanisms may also be utilized.

After the guide bar assembly 120 is axially locked to the end-effector90, the guide bar assembly 120 may be rotated to the desired location.As shown in FIG. 8B, the first and second lateral wings 114, 116 may berotated about the longitudinal axis A of the guide tube 92. Once thedesired rotational position is obtained, the rotational movement of theassembly 102 may be fixed with a central wheel handle lock 140. Thecentral wheel handle lock 140 may have a threaded stud 148 mounted intoa threaded hole in the guide bar assembly 120. Rotation of the centralwheel handle lock 140 tightens, holds, and locks the final position ofthe guide bar assembly 120. It will be appreciated that another suitablelock may also be utilized to secure the guide bar assembly 120.

With emphasis on FIGS. 9A-9B, after the rotational position has beenlocked, the width and/or angulation of the first and second navigatedcannulas 120, 122 may be independent adjusted. The first and secondlateral wings 114, 116 may be curved or angled to allow for angularadjustments of the cannulas 120, 122 as the cannulas 120, 122 move alongthe lateral wings 114, 116. For example, the first and second lateralwings 114, 116 may be curved or angled such that the terminal ends ofthe wings 114, 116 point downwards, thereby providing for a greaterdegree of angulation as the cannulas 120, 122 move further from thecentral guide bar 110.

Each of the first and second lateral wings 114, 116 may include anelongate slot 142 for securing the respective first and second navigatedcannula assemblies 104, 106. The navigated cannula assemblies 104, 106may slide along the respective slots 142 to adjust the width and/orangulation of the cannulas 120, 122. As best seen in FIG. 8B, a topsurface of the wings 114, 116 may each include graduations, an indicatorscale, or other markings 144 to provide visual feedback on the distanceand/or angle of the cannulas 120, 122. For example, each graduated scale144 may range from 10-24° in increments of 2° for each cannula 120, 122.An opening 150 in the top face of support arm 124, 126 of the cannulaassembly 104, 106 may provide an exact reading of the graduated markingon the indicator scale 144.

The cannula assemblies 104, 106 may move along one or more ratchets 146.The ratchets 146 may include linear or curvilinear ratchets 146configured to mimic the shape of the lateral wings 114, 116. Theratchets 146 may be positioned above and below the elongate slots 142.The ratchets 146 may include a rack and pinion system for independentlymoving the cannula assemblies 104, 106 along the lateral wings 114, 116.The ratchets 146 may provide for incremental adjustment of the widthand/or angle of the cannulas 120, 122. For example, the angle of thefirst cannula 120 may be aligned to match the desired location of thefirst lateral leg 20 of the implant 12 and the angle of the secondcannula 122 may be aligned to match the desired location of the secondlateral leg 22 of the implant 12. In addition, the width between thefirst and second cannulas 120, 122 may be matched to the desired widthbetween the lateral legs 20, 22 of the implant 12. The width and/orangle of the cannulas 120, 122 may each be independently locked with arotatable knob 152. Rotation of each of the knobs 152 tightens, holds,and locks the final position of each of the cannulas 120, 122. It willbe appreciated that any suitable lock may be utilized to secure thecannulas 120, 122.

The bi-portal assembly 100 may include a plurality of tracking markers108, such as passive spherical markers, configured to monitor theposition of the guide bar assembly 102 and first and second navigatedcannula assemblies 104, 106, respectively. In the embodiment shown, ninemarkers 108 are used to track the locations and positions of thecomponents, but it will be appreciated that any suitable number andconfiguration of markers may be selected. The distal end of the guidebar 110 may include a first tracking marker 108. The terminal end offirst lateral wing 114 may include a second tracking markers 108 and theterminal end of the second lateral wing 116 may include a third trackingmarker 108. The bottom of the first supporting arm 124 may include afourth tracking marker 108 and the bottom of the second supporting arm126 may include a fifth tracking marker 108. The first navigated cannula120 may include sixth and seventh tracking markers 108 aligned along thecentral longitudinal axis A1 of the cannula 120. The second navigatedcannula 122 may include eighth and ninth tracking markers 108 alignedalong the central longitudinal axis A2 of the cannula 122. In thismanner, the tracking markers 108 are configured to provide informationto the robot system 80 regarding the cannulas 120, 122 and the bi-portalassembly 100, such as the location, orientation, distance, angles, andother relevant information.

Turning now to FIGS. 10, 11A-11B, and 12A-12B, each cannula assembly104, 106 may include an adjustable stop 160, 162 configured to set theaccess depth into the surgical site. Depth control may be setindependently for each of the trajectories for customized access, forexample, for abnormal patient anatomy. Each stop 160, 162 may include asleeve or tubular body configured to slide over or along the respectivecannula 120, 122. The stop 160, 162 may slide along an elongate slit 164extending along the central longitudinal axis A1, A2 of the cannula 120,122. A pin or other engagement member from the stop 160, 162 may bereceivable in the slit 164 to guide the stop 160, 162 to the desireddepth. The depth may be locked with a lever latch 166. The lever latch166 may include a pair of pivotable thumb latches positioned on oppositesides of the cannula 120, 122. When depressed and squeezed together, thelever latch 166 allows the depth stop 160, 162 to slide along the lengthof the cannula 120, 122. When released, the lever latch 166 locks theposition of the depth stop 160, 162, thereby providing a maximum accessdepth for any instruments placed through the cannula 120, 122. For theembodiment shown in FIG. 10 , the right trajectory along axis A1provides for deeper access to the disc space 4 than the left trajectoryalong axis A2. It will be appreciated that the stops 160, 162 may beindependently adjusted to provide the same or different access depths.Alternatively, instead of manual control, the robot 82 may control andauto-generate the width, angulation, and/or adjustable depth controlsettings for the cannulas 120, 122.

With emphasis on FIGS. 11A-11B, a navigated instrument 170 may bepositioned through each cannula 120, 122 to access the surgical site.The navigated instrument 170 may extend from a proximal end 172 with ahandle configured to be gripped by a user to a distal end 174 with a tipconfigured to access the surgical site. The navigated instrument 170 mayinclude an array 176 with a plurality of tracking markers 178, such asspherical passive markers, configured to identify and monitor movementof the instrument 170 by the navigation and robotic system 80. Thenavigated instrument 170 may be compatible with dilators, off-centersheaths, docking facet dilators, and other instrumentation. FIGS.12A-12B show instruments 180 positioned through cannulas 120, 122,respectively. The stops 160, 162 may be adjusted with theinstrumentation 180 present. By removing the navigated array 176,instruments 180 may provide improved visualization of the surgical site.

With emphasis on FIGS. 13A-13C, direct visualization port assemblies190, 192 are shown according to one embodiment. The direct visualizationport assemblies 190, 192 may replace the cannula assemblies 104, 106 toincrease visualization of the neural elements during decompression. Thefirst lateral wing 114 of the guide bar assembly 102 supports the firstport assembly 190 and the second lateral wing 116 of the guide barassembly 102 supports the second port assembly 192. Each of the portassemblies 190, 192 may include an access port 194, a moveableattachment assembly 196, and an extension arm 198 connecting the accessport 194 to the attachment assembly 196. In the same manner as thecannula assemblies 104, 106, the attachment assemblies 196 may slidealong the respective slots 142 through the first and second lateralwings 114, 116 to adjust the width and/or angulation between the portassemblies 190, 192. As shown in FIG. 13A, each attachment assembly 196and access port 194 may be aligned along a central longitudinal axis B1,B2.

The access port 194 may include a hollow tubular body for accessing thesurgical site. The port 194 may be attached to the distal end of theextension arm 198 with a collar 202 that provides for a pivotable jointat the proximal end of the access port 194. The collar 202 may have aconical, spherical, or other suitable interface with the port 194 toallow for independent angulation of the port 194. As shown in FIG. 13B,the right port 194 is able to angulate laterally outward and off-axis oflongitudinal axis B1. In FIG. 13C, the right port 194 is able toangulate inwardly toward mid-line but still off-axis of longitudinalaxis B1. It will be appreciated that both the left and right ports 194have independent angulation based on the desired access to the surgicalsite. The depth of the ports 194 may also be controlled via theextension arms 198. The extension arm 198 may translate the port 194toward or away from the surgical site, thereby providing for customizedadjustability of each of the ports 194. Accordingly, the width andangulation between the ports 194, the conical angulation of the ports194, and the depth of the ports 194 may be adjusted to increasevisualization and improve safety around the neural elements of thespine.

FIGS. 14A-14D depict a navigatable instrument assembly 210 according toone embodiment. The navigatable instrument assembly 210 may include aninstrument 212 and adjustable stop 160. Although stop 160 is described,it will be appreciated that stop 162 is the same or another suitablestop may be substituted. The instrument 212 may include a body thatextends from a proximal end 214 configured to attach to a powered handleto a distal end 216 having the instrument tip. The instrument tip 216may include burrs, drills, osteotomes, reamers, or other suitableinstruments for cutting and/or removing bone. The instrument 212 may bepowered to provide for high-speed, oscillating, or other suitablepowered tips 216. The shaft 218 of the instrument 212 may support anarray 220 having a plurality of tracking markers 222, such as sphericalpassive markers, configured to identify and monitor movement of theinstrument 212 by the navigation and robotic system 80. The shaft 218 ofthe instrument 212 is receivable through a securing sleeve 222 whichattaches the adjustable stop 160 to the instrument 212. The securingsleeve 222 is positioned through the tubular body of the adjustable stop160. The securing sleeve 222 includes an enlarged neck 226 at itsproximal end configured to abut the proximal end of the stop 160 whenreceived therethrough. The securing sleeve 22 includes one or moreribbed portions 228 configured to interface with the pivotable thumblatches of the lever latch 166, thereby securing the position of thestop 160. The instrument assembly 210 may be navigated alone or througha cannula, such as one of the navigated cannulas 120, 122, to performthe surgical procedure.

Turning now to FIGS. 15A-15C and 16A-16B, an adjustable implant cannula230 is shown according to one embodiment. The adjustable implant cannula230 includes a hollow cannula body 232 and an adjustable threaded cap234. The cannula body 232 extends from a proximal end 236 to a distalend 238. The proximal portion 236 may be externally threaded to engagewith the internally threaded cap 234. As the cap 234 is rotated theoverall length of the implant cannula 230 is adjusted. An indicator 240may be used to set the adjustable implant cannula 230 to a planneddepth. The indicator 240 may include a window through the threaded cap234 and a marking that can be aligned to a graduated value, such asbetween 0 and 12 in increments of 2. After the depth has been set, thecannula dilator 242 may be loaded into the implant cannula 230 as shownin FIG. 15C. The cannula dilator 242 may include a cap 244 at itsproximal end and a distal tip 246 configured to expand. The distal tip246 of the cannula dilator 242 may be keyed into a corresponding recess248 at the distal end 238 of the cannula body 232.

As shown in FIG. 16A, the adjustable implant cannulas 230 may bepositioned through the navigation cannulas 120, 122. In FIG. 16B, eachcannula dilator 242 is positioned through the implant cannula 230. Toassemble, the cap 244 of the dilator 242 may be impacted until the cap244 hits the face of the navigation cannula 120, 122 and the implantcannula 230 may simultaneously lock into the navigation cannula 120, 122at the planned depth. The dilators 242 may then be expanded to create orenlarge a space in the bone. After the dilators 242 are removed, theimplant cannulas 230 may be used for the discectomy.

Turning now to FIGS. 17A-17B, a navigatable discectomy instrument 250 isshown according to one embodiment. The navigatable discectomy instrument250 includes an elongate stationary body 252, an elongate slidable body254 abutting the stationary body 252, a stationary handle 256 connectedto the stationary body 252, an articulating grip 258 pinned to thestationary handle 256, and an articulating distal tip 260 configured tocut bone. When the articulating grip 258 is squeezed toward thestationary handle 256, the slidable body 254 translates longitudinallyalong the stationary body 252 to thereby pivot the articulating tip 260about a pivot pin. FIG. 17A shows the articulating tip 260 in an openextended position and FIG. 17B shows the articulating grip 258 squeezedinwardly to pivot the tip 260, thereby folding the tip 260 toward thestationary body 252 to cut and remove soft tissue.

The navigatable discectomy instrument 250 may include one or moretracking markers 264, 268 to track the placement and orientation of theinstrument 250 and the articulation of the discectomy tip 260. Thestationary body 252 may support a tracking array 262 with a plurality oftracking markers 264, such as spherical passive markers, identified andmonitored by the navigation and robotic system 80. In addition, apivotable arm 266 may support a single marker 268, which moves when thearticulating grip 258 is squeezed. The single marker 268 is thusmoveable relative to the array 262 of stationary markers 264. As shownin FIG. 17A, the single marker 268 has a first position pointingproximally when the articulating tip 260 is extended distally. When thegrip 258 is squeezed and the tip 260 is pivoted, the single marker 268pivots to a second position pointing distally as shown in FIG. 17B. Inthis manner, the navigation and robotic system 80 is able to trackplacement and articulation of the distal tip 260 to confirm soft tissueremoval and endplate preparation. This may be used to enhance thediscectomy by helping confirm placement and orientation.

As shown in FIGS. 18A-18C, a discectomy may be performed with thediscectomy instrument 250. After the implant cannulas 230 are insertedand locked axially in the navigated cannulas 120, 122, a discectomy maybe performed through both implant cannulas 230 to increase theefficiency and overall quality of soft tissue removal. In FIGS. 18A-18C,a pair of discectomy instruments 250 are inserted through the implantcannulas 230 and into the disc space 4 and the articulating tips 260 arepivoted to remove soft tissue. The dual discectomy may lead to easierinterbody insertion and positioning, and may increase the volume of bonegraft in the disc space to promote faster fusion. The discectomyinstrumentation 250 may utilize navigation to track placement andarticulation at the distal tip 260 to confirm soft tissue removal andendplate prep in auto-generated volumetric space of the disc.

With emphasis on FIGS. 19A-19B and 20A-20C, a powered discectomyinstrument 270 is shown according to another embodiment. The discectomyinstrument 270 may be powered, for example, by a motor, to provide forenhanced removal of disc material between the endplates of adjacentvertebrae. The powered discectomy instrument 270 may include anarticulating soft tissue cutter, curette, or cutting tip 272 that may beconfigured to release both the nucleus pulpous and annulus fibrosus fromthe inferior and superior endplates of the vertebrae 2 simultaneously.As shown in FIGS. 19A-19B, the discectomy instrument 270 includingcutting tip 272 is configured to fit through the implant cannulas 230 toaccess the disc space 4. The cutting tip 272 may be articulated to reacharound the disc space 4. Although only one implant cannula 230 andinstrument 270 is shown, it will be appreciated that the instrument 270may be used on the contralateral side alone or simultaneously with theipsilateral side for a bi-portal discectomy.

As shown in FIGS. 20A-20C, the cutting tip 272 may include upper andlower endplates 274, 276 with a plurality of teeth configured to cut andrelease disc material. The cutting tip 272 of the discectomy instrument270 may be configured for passive expandability. The upper and lowerendplates 274, 276 may be able to expand away from one another. As thedisc material is cut, released, and evacuated, space is created betweeninferior and superior endplates of the vertebrae 2. One or more springcuts 278 in the cutter 272 may allow for the passive expansion. As bestseen in FIG. 20C, the spring cut 278 may be bifurcated by a central slit280, which provides built in clearance for the cutter 272 in itscollapsed state.

Turning now to FIGS. 21A-21F, a method of inserting and positioning theexpandable interbody implant 12 is shown according to one embodiment.The interbody implant 12 may be positioned into the disc space 4 with afirst inserter 300 by inserting the interbody 12 through one implantcannula 230, using a cable 296 to fish the lateral leg 20 of the implant12 to the opposite implant cannula 230, and connecting the secondinserter 302 through the opposite implant cannula 230. A cable assembly292 threaded onto one leg 20 of the implant 12 may use a magnet 294 topull the interbody 12 into its natural U-shaped position with theproximal ends of the lateral legs 20, 22 connected to inserters 300, 302through the respective implant cannulas 230.

With emphasis on FIG. 21A, an articulated magnet retrieval anddeployment tool 290 may be deployed through the contralateral implantcannula 230. The articulated magnet tool 290 may be articulated to guidethe tool 290 toward the ipsilateral implant cannula 230. The articulatedmagnet tool 290 may magnetically attract and connect to a magnetic tip294 of the cable assembly 292 positioned through the ipsilateral implantcannula 230. The cable assembly 292 includes the magnetic tip 294attached to a fishing cable 296. The fishing cable 296 may include acable, wire, rope, chain, or other suitable line configured to be fishedbetween the implant cannulas 230. The fishing cable 296 may have acrimped end at the magnetic tip 294. The opposite end of the fishingcable 296 may be coupled to the end of the lateral leg 20 of the implant12. For example, the fishing cable 296 may be secured to the implant 12with a proximal threaded cap 298.

As shown in FIG. 21B, the articulated magnet tool 290 is retracted backthrough the contralateral implant cannula 230, thereby pulling themagnetic tip 294 and attached cable 296 into the contralateral implantcannula 230. After articulating the magnet retrieval tool 290 to connectand pull the crimped end of the cable assembly 292 through thecontralateral implant cannula 230, the cable 296 may be placed undertension as an ipsilateral inserter instrument 300 is rigidly connectedto the second lateral leg 22 of the implant 12.

In FIG. 21C, the implant 12 is fed through the ipsilateral implantcannula 230 via inserter 300 with the cable assembly 292 still attachedto the opposite end of the implant. 20. The implant 12 articulates atpins 26. As shown in FIG. 21D, the cable 296 may help to pull theinterbody 12 into its articulated U-shaped position with the laterallegs 20, 22 bent at pins 26 to increase the overall width or footprintof the implant 12. The threaded cap 298 may be aligned to the outlet ofthe contralateral implant cannula 230. It may be desirable to check therigidity of inserter connection before unthreading proximal threaded cap298 from the interbody 12 to release the cable assembly from interbody12.

FIG. 21E shows a view of the inserters 300, 302 with the cannulas 230omitted for clarity. The inserters 300, 302 may each include an outersleeve 304 with a shaft 306 extending therethrough. The terminal end ofthe shaft 306 may provide for threaded engagement with the end of thelateral leg 20, 22 of the implant 12. In FIG. 21E, the threaded sleeve304 and counter torque shaft 306 of the second inserter instrument 302is positioned through the contralateral implant cannula 230. In thefinal configuration shown in FIG. 21F, the second inserter 302 isthreaded onto the contralateral leg 20 of the implant 20 while the firstinserter 300 is still rigidly connected to the ipsilateral leg 22 of theimplant 20. This dual connection provides for dual interbody control ofthe implant 12. Thus, the overall position of the implant 12 and each ofthe lateral legs 20, 22 may be manipulated or moved by both inserters300, 302.

FIG. 22 shows a complete overview of the bi-portal assembly 100 withboth navigable inserters 300, 302. The guide bar assembly 102 securesthe first and second navigated cannula assemblies 104, 106 along thedesired trajectories. The implant cannulas 230 are positioned throughthe respective navigated cannula assemblies 104, 106. The inserters 300,302 are positioned through the respective implant cannulas 230. Onceboth inserters 300, 302 are connected to the lateral legs 20, 22 of theimplant 12, navigable arrays 308 may be attached to the inserters 300,302 for precise placement of the interbody 12, thereby providing forsuperior segmental correction and stabilization.

Turning now to FIG. 23A-23B, once the collapsed interbody implant 12 isaccurately placed and positioned, drivers 310 may be placed through theinserters 300, 302 to expand the implant 12. After the handle and array308 of the inserter 300, 302 is removed, the drivers 310 may be placeddown both the ipsilateral and contralateral inserters 300, 302 andclipped in axially to the respective inserters 300, 302. The distal tipof each driver 310 may interface with the actuation members 30 of theimplant 12 to allow for independent expansion of the lateral legs 20, 22of the implant 12. The handle of the driver 310 may be rotated to rotatethe actuation member 30, thereby expanding the respective leg 20, 22 ofthe implant 12. Arrays and/or smart instrumentation may be utilized toensure parallel, lordotic, coronal, or other desired expansion for theimplant 12.

Turning now to FIGS. 24A-24C and 25A-25F, after the interbody 12 isimplanted, the pedicle-based intradiscal fixation implants 14 may beinstalled. FIGS. 24A-24C show a rod fixation instrument 320 according toone embodiment. The rod fixation instrument 320 is configured to loadand deploy the rod 40 of the pedicle-based intradiscal fixation implant14. The rod fixation instrument 320 may include a body 322 with adeployment tube 324 at its distal end. The deployment tube 324 isstraight and configured to draw in the curved rod 40, therebystraightening the rod 40 when held within the deployment tube 324. Theinstrument 320 may load the nitinol rod 40 into the straight deploymenttube 324 by drawing the rod 40 in from the threaded proximal end 48. Thedeployment tube 324 may be customized for specific size offerings as thebend diameter, or cephalad-caudal height, of the nitinol rod 40 may havea proportional rod thickness to improve super elastic properties inproportion to its strength.

The rod fixation instrument 320 may include a T-shaped handle 326 with asocket 328 configured to be received over a shaft 330 with an impactioncap 336. The socket 328 snaps in drive engagement with button 332. Whenthe handle 326 is rotated about the longitudinal axis of the instrument320, the nitinol rod 40 is drawn into the deployment tube 324. Thehandle 326 may be released by snap release of the drive engagementbutton 332. As shown in FIG. 24C, after the guide bar assembly 102 hasbeen removed from the guide tube 92 of the end-effector 90, the nitinoldeployment instrument 320 is subsequently positioned through the guidetube 92 of the end-effector 90. The instrument 320 may be locked intothe axial locking cap 130 by an outer circumferential groove 334 in thebody 322 of the instrument 320.

As shown in FIGS. 25A-25B, the rod fixation instrument 320 is set intoposition for deploying the rod 40. The end-effector 90 is set inposition after the posterior of the spine is accessed. A hole may bepre-drilled into the pedicle 8 of the inferior vertebra 2. The nitinolrod 40 may be set into the prepped hole, locked into the end-effector90, and ready for impaction for deployment.

In FIGS. 25C-25D, the nitinol rod 40 is deployed through the inferiorvertebral body 6, through the disc space 4, and into the superiorvertebral body 6. The shaft 330 of the deployment instrument 320 may betranslated distally along the longitudinal axis of the instrument 320,for example, by striking the impaction cap 336 with a surgical mallet.The shaft 330 forces the nitinol rod 40 to deploy out of the deploymenttube 324. The properties of super elastic nitinol allow for the nitinolrod 40 to return to its natural, curved state throughout the deploymentprocess, sweeping from the inferior pedicle 8, thru the intradiscalspace 4, medially to the lateral interbody legs 20, 22, and into thesuperior vertebral body 6. After the impaction cap 336 bottoms-out, therod 40 is fully deployed, and the deployment instrumentation 320 may beremoved.

In FIGS. 25E-25F, the pedicle screw 42 is secured and anchored to thenitinol rod 40. A driver 340 positioned through guide tube 92 insertsthe pedicle screw into the inferior pedicle 8. The pedicle screw 42 isinserted and driven over the proximal threads 48 of the nitinol rod 40to purchase the existing cortical bone in the pedicle 8 and anchor theproximal end 44 of the nitinol rod 40 to the inferior pedicle 8. Theprocess shown in FIGS. 25A-25F may then be repeated for the secondintradiscal fixation implant 14 on the contralateral side.

FIGS. 26A-26D show an example of the completed construct 10 includingthe interbody implant 12 and two intradiscal implants 14. FIG. 26Aprovides a posterior view of the spine and the two intradiscal implants14 positioned into the pedicles 8 of the inferior vertebra 2. FIG. 26Bshows a lateral view of the spine with the interbody implant 12positioned in the disc space 4 between the vertebrae 2. FIG. 26C showsan anterior view of the spine and the interbody implant 12. FIG. 26D isan intradiscal view of the system 10 including the interbody implant 12and two intradiscal implants 14. The completed construct 10 providessuperior stabilization from a posterior approach. The intradiscalimplants 14 do not violate the superior facet joint, limiting adjacentsegment disease that can be a result of superior adjacent facetviolation.

According to one embodiment, the procedure may be performed withnavigation and/or robotic assistance. The robotically-enabled proceduremay include a workflow assisted and enhanced using imaging, navigationand robotics including: (1) pre-operative planning; (2) end-effectorset-up; (3) tubular access and decompression or alternativevisualization port workflows; (4) bi-portal implant cannula insertion;(5) bi-portal discectomy; (6) interbody deployment, positioning, andexpansion; (7) nitinol fixation construction; and (8) finalverification. The robotically-enabled procedure may utilize imaging,navigation, and robotics to enhance the quality and efficiency of theposterior procedure through planning and navigable instrumentation.

The first step in the workflow may include pre-operative planning. Theimportance of a structured workflow for the robotically-enabledbi-portal interbody fusion technique is stressed in pre-operativeimaging and planning stages. A step-by-step user interface may beprovided on the monitor 88 of the robot 80 to walk healthcareprofessionals through precise interbody placement, depth-controlledaccess-decompression instrumentation, and fixation planned deployment.The control of these aspects may be enhanced with sagittal, axial,coronal, and 3D volumetric views of patient anatomy with the addition ofCT-MRI merge displays to recognize and visualize neural elements forsafe and repeatable procedures.

The planning stage may follow a detailed checklist. After selecting thelevel to be corrected on the monitor 88, a virtual representation of theanterior or center leg 24 of the 3-legged interbody implant 12 may beplaced along the anterior side of the apophyseal ring on midline. Thisinterbody 12 has dual, independent expansion and angulation on thelateral legs 20, 22. The interbody 12 may utilize bi-portal access intothe disc space 4 based of the width of the anterior leg 24 andangulation and length of the lateral legs 20, 22. Angulation of laterallegs 20, 22 may be controlled on the transverse plane on the plannedlevel, shifting from medial to lateral. Parallel and lordotic expansionof the lateral legs 20, 22 may be planned prior to the procedure eitherindependently or mirrored to one another. All sizing, positioning, andexpansion of the interbody footprint are to help customize thecorrection to patient anatomy.

Once the planned anterior width and leg angulation are set, a surgeonmay plan for the removal of posterior bone anatomy to gain access intothe disc space 4. For example, pre-planned depth stops may be used foraccess instrumentation on the given trajectory. In one embodiment, stops160, 162 may be set to protect neural anatomy from poweredinstrumentation. The planned implant cannula depth may be setindependently in relation to the proximal ends of the left and rightlateral legs 20, 22 of the interbody 12.

The final stage in the pre-op planning checklist is to plan the nitinolfixation implants 14 with regards to trajectory, rod sizing, and pediclescrew sizing. The nitinol fixation implant 14 may be set medially to thelateral legs 20, 22 and posteriorly to the anterior leg 24 of theinterbody 12. Size offerings are determined based on which bend diameterfits within the inferior and superior vertebral bodies 6 withoutviolating the facet or damaging the axis of the pedicle 8 of thesuperior vertebra 2. Pedicle screws 42 may be sized to ensure thecapture of the proximal end 44 of the nitinol rod 40 with the screw 42while the screw head 50 is protruding from the pedicle 8.

The second step in the workflow may include end-effector manual set-up.Once the pre-op plan summary is complete, the guide bar assembly 102 maybe introduced to the end-effector 90 to introduce single position,bi-portal control. The axial locking cap 130 may be snapped on an insideportion of the end-effector 90 to avoid blocking the infrared LEDs 132.The guide bar 110 may be slid through the inner diameter of the guidetube 92 of the end-effector 90 to lock the assembly axially with theend-effector height. In an alternative design, the connection to therobot 82 could be built into the guide bar 110 rather connecting throughthe end-effector 90.

Once the guide bar 110 snaps in and locks axially, the assembly 100 maybe rotated about the end-effector 90 until the planned levels plane isparallel with the navigated cannulas 120, 122. Markers 108 areidentified by the camera system 94 to callout the degrees off the plane,and the guide bar 110 may be final locked when the callout is at 0°.Following rotationally locking the guide bar 110, the width of the guidebar assembly 102 may be manually adjusted to match the anterior legswidth and then angles of the navigated cannulas 120, 122 may be adjustedto be consistent with the pre-op plan, sizing, and positioning. Axis ofthe navigated cannula 120, 122 may line up with the medial-lateral angleof the lateral leg 20, 22 found in the plan summary. The navigatedcannulas 120, 122 may be final locked to ensure guide bar and navcannula rigidity before moving forward to depth control.

Working with an outside-in approach, access-decompression may begin toremove the bilateral facet joints. Safety and protective precautions maybe taken for exiting neural elements, for example, by setting theadjustable stop 160, 162 to its initial depth. Depth control may be setaccording to plan and remains independent on the left and righttrajectories for customized access for abnormal patient anatomy. Analternative design to this manual set-up is providing power to a singleposition, bi-portal end-effector that can auto-generate the width,angulation, and adjustable depth control settings according to thepre-operative plan.

The third step in the workflow may include tubular access anddecompression or alternative direct visualization ports. There remainsvariability in surgeons' comfort with the tubular approach in comparisonto direct visualization while removing posterior structural anatomy andprotecting neural elements anteriorly to the facet joint. Toaccommodate, alternative workflow consisting of direct visualizationports 194 can be utilized with the guide bar system 102 in addition tothe tubular access and decompression workflow. Hybrid use of high-speedburrs, oscillating drills, and manual osteotome instrumentation may beutilized to enhance comfort for surgeons from different technicalbackgrounds and training. Alternative workflows keep the same trajectoryplanned with benefits provided with each workflow.

The MIS access workflow with the navigated cannulas 120, 122 providestubular access and decompression benefits including: (1) depth controlcompatibility; (2) navigated cannula compatibility with dilator,off-center sheath, docking facet dilator, and instrumentation; (3)reduced amount of posterior structural anatomy; and (4) streamlined toinsert interbody cannula immediately. The direct visualization accessworkflow with ports 194 may have conical angulation. The directvisualization may provide for increased visualization for thoroughdecompression and increased visualization may increase safety withregards to neural elements.

The fourth step in the workflow may include bi-portal implant cannulainsertion. After a thorough access and decompression have sufficientlyremoved all obstructing bone from the bilateral trajectories, regardlessof access workflow used, navigated cannulas 120, 122 may be used withthe adjustable stop 160, 162 locked into its lowest height for implantcannula insertion. Implant cannula 230 may be adjusted to planned depthaccording to plan, and then cannula dilator 242 may be loaded into thekeyed feature 248 at the distal tip 238 of the cannula 232. The proximalend of cannula dilator 242 may be impacted until the cap 242 hits theface of the navigated cannula 120, 122, and implant cannula 230simultaneously locks into the navigated cannula 120, 122 at the planneddepth. The cannula dilator 242 may be removed to begin the discectomy.

The fifth step in the workflow may include the discectomy. Once bothimplant cannulas 230 are inserted and locked axially, a discectomy maybe performed through both implant cannulas 230 to increase theefficiency and overall quality of soft tissue removal. This may lead toeasier interbody insertion, positioning and increase the volume of bonegraft in the disc space to promote faster fusion. A heat map may beautomatically generated based on interbody placement to calculate avolumetric area where tools can and should be placed to remove softtissue.

Discectomy instrumentation 250 may utilize navigation to track placementand articulation at the distal tip 260 to confirm soft tissue removaland endplate prep in auto-generated volumetric space of the disc. Thearray sphere 268 may track the mechanical articulation according to thecustomized array positioning. This may enhance the discectomy by helpingconfirm placement and orientation. The robot 82 may also read out areasin which a tool path has or has not passed through to ensure sufficientsoft tissue removal and surface area of endplates have been prepped.

Bi-portal navigated discectomy may have variability in techniqueallowing for surgeon preference to select between navigated manualinstrumentation 250, powered discectomy instrumentation 270, or a hybriduse of both. Both technique workflows may be completed with manualendplate prep instrumentation to help ensure increased fusion rates andto verify the passing of instrumentation throughout the auto-generatedvolumetric heat map.

The sixth step in the workflow may include interbody deployment andpositioning. After a thorough discectomy is completed, the 3-leggedinterbody 12 may be positioned by inserting the interbody 12 through theipsilateral implant cannula 230, using a cable 292 to fish thecontralateral lateral leg 20 to the contralateral implant cannula 230,and connecting the second inserter 302 through the contralateral implantcannula 230. Utilizing two hinge pins 26 to connect the three legs 20,22, 24 and a cable assembly 292 threaded onto the contralateral leg 20,a magnet pulls the interbody 12 into its natural U-shaped position withthe proximal ends of the lateral legs 20, 22 connected to inserters 300,302 through the implant cannula 230.

After articulating the magnet retrieval tool 290 to connect and pull thecrimped end of the cable assembly 292 through the contralateral implantcannula 230, the cable 296 may be placed under tension as thecontralateral inserter 300 is rigidly connected to the lateral leg 22.Rigidity of inserter connection may be checked before unthreading theproximal threaded cap 298 from the interbody 12 to release the cableassembly 292 from the interbody 12.

Once both inserters 300, 302 are connected to the lateral legs 20, 22,navigable arrays 308 may be attached to the inserters 300, 302 forprecise placement of the interbody 12 for superior segmental correctionand stabilization. Views from the sagittal, axial, and coronal planes aswell as a 3D volumetric view may enhance a surgeon's ability to placethe interbody 12 in the planned position with dual inserter control.Trajectories may be locked as a result of the pre-op plan and guide barset-up, but depth and orientation of the anterior and lateral legs 20,22 may be confirmed using navigation prior to expansion.

Once the collapsed interbody 12 is accurately placed, drivers 310 may beplaced down both the ipsilateral and contralateral inserters 300, 302and clipped in axially to the respective inserters 300, 302. Arraysand/or smart instrumentation may be utilized to read-out both parallel,followed by lordotic, expansion for both the left and right sidesindividually. Same as the rest of the procedure, the planned summary maylist the expandable implant's target height, lordotic, and coronalcorrection.

The seventh step in the workflow may include installing the nitinolfixation assembly 14. As a result of superior segmental correction fromthe interbody stabilization device 12 with increased cortical bone onthe apophyseal ring contact with interbody endplates, inferiorpedicle-based intradiscal fixation devices 14 may be deployed mediallyto the lateral legs 20, 22 of interbody plan. The super elasticity ofnitinol allows for the material to be drawn into the straight deploymenttube 324 from its curved state. The instrument 320 is able to load thenitinol into the straight deployment tube 324 by drawing it in from thethreaded proximal end 48. The deployment tube 324 is customized forspecific size offerings as the bend diameter, or cephalad-caudal height,of the nitinol rod 40 has a proportional rod thickness to improve superelastic properties in proportion to its strength.

Before shifting the end-effector 90 onto the planned trajectory forfixation deployment, navigation may prompt the surgeon to re-registerwith a sagittal and coronal c-arm shot to account for the segmentalcorrection and a shift of inferior and superior vertebrae 2 frominterbody expansion. Once re-registered, the pre-op plan for nitinolfixation 14 may be confirmed and/or altered to fit revised patientanatomy. Once the plan is set, the end-effector 90 moves into positionand a powered pedicle prep drill may be used to drill a hole to theplanned depth of the deployment instrumentation 320 into the inferiorpedicle 8. The nitinol deployment instrument 320 is subsequently sentdown the end-effector 90 and locked into the axial locking cap 130 afterthe guide bar assembly 102 has been removed.

The nitinol rod 40 may be set into the prepped hole, locked into theend-effector 90, and is ready for impaction for deployment. Theproperties of super elastic nitinol allow for the nitinol to return toits natural, curved state throughout the deployment process, sweepingfrom the inferior pedicle 8, thru the intradiscal space 4, medially tothe lateral interbody legs 20, 22, and into the superior vertebral body6. After the impaction cap 336 bottoms-out and the rod 40 is fullydeployed, the instrumentation 320 may be removed. The pedicle screw 42may be inserted and driven over the proximal threads 48 of the nitinolrod 40 to purchase the existing cortical bone in the pedicle 8 andanchor the proximal end 44 of the nitinol rod 40 to the inferior pedicle8. Additional features may be used to lock the screw 42 to the nitinolrod 40, such as a snap ring in the pedicle screw 42 to snap into anexternal groove of the nitinol rod 40. The process of installing thesecond nitinol fixation assembly 14 may be repeated for thecontralateral side.

The eighth step in the workflow may include final verification. Afterfixation 14 is deployed and assembled, a final verification may be usedto ensure the final construct accomplished the pre-op plan targetedpositions, and achieved segmental correction in the sagittal and coronalplanes. The completed construct provides superior stabilization from aposterior approach and the fixation devices 14 do not violate thesuperior facet joint, thereby limiting adjacent segment disease.

The robotically-enabled procedure utilizes imaging, navigation, androbotics to enhance the quality and efficiency of the posteriorprocedure through planning and navigable instrumentation. The overallprocedure may reduce radiation exposure compared to traditionalsurgeries. The bi-portal assembly and discectomy instruments provide forsafe and repeatable direct decompression within the access window of thetubular approach. The discectomy instrumentation may increase thepercent volume of soft tissue removed to increase volumetric area forinterbody placement and bone graft. Segmental correction from theinterbody stabilization device with independently controlled sagittaland coronal correction may provide for increased stability fromincreased endplate contact along the apophyseal ring. The posterior, MISnitinol fixation implants avoid violation of superior facet joint andthe potential iatrogenic effects bilateral pedicle constructs can cause.

Although the invention has been described in detail and with referenceto specific embodiments, it will be apparent to one skilled in the artthat various changes and modifications can be made without departingfrom the spirit and scope of the invention. Thus, it is intended thatthe invention covers the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents. It is expressly intended, for example, that all componentsof the various devices disclosed above may be combined or modified inany suitable configuration. cm What is claimed is:

1. A method for stabilizing the spine comprising: positioning anexpandable interbody implant in a disc space between superior andinferior vertebrae, the expandable interbody implant having threearticulating and expandable legs; deploying a first bendable rod from anipsilateral pedicle of the inferior vertebra, thru the disc space, andinto a vertebral body of the superior vertebra; inserting a firstpedicle screw through the ipsilateral pedicle of the inferior vertebraand driving the first pedicle screw over the first bendable rod toanchor the first bendable rod; deploying a second bendable rod from acontralateral pedicle of the inferior pedicle, thru the disc space, andinto the vertebral body of the superior vertebra; and inserting a secondpedicle screw through the contralateral pedicle of the inferior pedicleand driving the second pedicle screw over the second bendable rod toanchor the second bendable rod.
 2. The method of claim 1, wherein thethree legs of the expandable interbody implant are articulated relativeto one another to increase the overall footprint of the implant.
 3. Themethod of claim 1, wherein the expandable interbody implant is placedalong the apophyseal ring of the vertebrae for cortical bone support. 4.The method of claim 1, wherein the expandable interbody implant isexpanded to independently control sagittal and coronal correction. 5.The method of claim 1, wherein the expandable interbody implant ispositioned in the disc space by inserting a magnetic cable assemblyattached to the expandable interbody implant through an ipsilateralcannula, inserting an articulating magnet retrieval tool through acontralateral cannula to magnetically attract and connect to themagnetic cable assembly, and retracting the articulating magnetretrieval tool back through the contralateral cannula, thereby pullingthe cable assembly into the contralateral cannula and positioning theexpandable interbody implant in the disc space.
 6. The method of claim1, wherein the first intradiscal implant is deployed through anipsilateral cannula and the second intradiscal implant is deployedthrough a contralateral cannula.
 7. The method of claim 1, wherein thefirst and second intradiscal implants are positioned medially relativeto the expandable interbody implant.
 8. The method of claim 1, whereinthe first and second bendable rods are each deployed with a deploymentinstrument having a deployment tube and a shaft with an impaction cap,wherein each bendable rod is deployed by striking the impaction cap,thereby forcing the rod to deploy out of the deployment tube.
 9. Amethod of installing an expandable interbody implant in a disc spacebetween two adjacent vertebrae comprising: inserting a cable assemblythrough an ipsilateral cannula, the cable assembly including a cablewith a magnetic tip at one end and attachable to an expandable interbodyimplant at the other end, the expandable interbody implant having afirst expandable lateral leg, a second expandable lateral leg, and athird central leg pivotably connected between the first and secondlateral legs; inserting an articulating magnet retrieval tool through acontralateral cannula; articulating and guiding the articulating magnetretrieval tool toward the ipsilateral cannula to magnetically attractand connect to the magnetic tip of the cable assembly; and retractingthe articulating magnet retrieval tool back through the contralateralcannula, thereby pulling the cable assembly into the contralateralcannula and positioning the expandable interbody implant in the discspace.
 10. The method of claim 9 further comprising threading the cableassembly on the first expandable lateral leg of the expandable interbodyimplant before inserting the cable assembly through the ipsilateralcannula.
 11. The method of claim 9 further comprising attaching a firstinserter to the expandable interbody implant while placing the cableunder tension.
 12. The method of claim 11 further comprising feeding theexpandable interbody implant through the ipsilateral cannula with thefirst inserter while the cable assembly pulls the expandable interbodyimplant into an articulated U-shaped position.
 13. The method of claim12, wherein after removing the cable assembly from the expandableinterbody implant, attaching a second inserter to the expandableinterbody implant such that the first and second inserters are rigidlyconnected to the first and second lateral legs, respectively, therebyproviding for dual control of the expandable interbody implant.
 14. Themethod of claim 13 further comprising inserting a driver through each ofthe first and second inserters to independently expand the first andsecond lateral legs to control sagittal and coronal correction.
 15. Amethod for installing a pedicle-based intradiscal implant comprising:loading a deployment instrument including a body having a longitudinalaxis with a straight deployment tube and a shaft with an impaction cap,by drawing a rod having a naturally curved shape into the straightdeployment tube, thereby straightening the rod when held within thedeployment tube; positioning the deployment tube at a pedicle of aninferior vertebra; and deploying the rod from the deployment instrumentby striking the impaction cap to translate the shaft of the deploymentinstrument along the longitudinal axis, thereby forcing the rod todeploy out of the deployment tube, wherein once deployed, the rodextends from the pedicle, thru a disc space, and into a vertebral bodyof a superior vertebra.
 16. The method of claim 15 further comprisingsecuring a pedicle screw through the pedicle of the inferior vertebraand driving the pedicle screw over one end of the rod to anchor the rod.17. The method of claim 16, wherein a proximal end of the rod includesan externally threaded portion configured to mate with an internallythreaded portion of the pedicle screw.
 18. The method of claim 15,wherein the rod is comprised of a shape-memory material.
 19. The methodof claim 15, wherein the rod is comprised of nitinol.
 20. The method ofclaim 15, wherein the curved shape of the rod is an arc up to 180°.